%0 Journal Article
%T Performance Evaluation of a Time
%A Christian Kargel
%A Petr Fomin
%J Applied Spectroscopy
%@ 1943-3530
%D 2019
%R 10.1177/0003702819831278
%X Plastics have many unrivaled properties and are thus indispensable materials with an ever-increasing production. Since the plastics recycling rates are still small, the plastic waste that ends up on landfills, in the environment including oceans, and incineration plants also steadily grows. Large-scale automated sorting of waste plastics may help solve the problem. However, most state-of-the-art approaches are limited to a (very) small number of plastic types that can be simultaneously sorted and have severe difficulties with black plastics. The labeling of plastics with fluorescent tracers (¡°markers¡±) during their production has the potential to enable the fast and highly reliable classification and automated sorting of many different plastic types simultaneously. Unfortunately, the unique marker fluorescence (¡°optical fingerprint¡±) might be obscured by the autofluorescence (AF) often emitted by plastics. Recently, we have shown that time-gated fluorescence spectroscopy (TGFS) can be successfully applied to eliminate the influences from AF. In this study, we present the prototype of a TGFS measurement system for the classification and sorting of plastics and evaluate its performance in a typical industrial situation. With 150£¿000 investigated plastics flakes from 10 different plastic types that were labeled with binary combinations of six fluorescent markers, an overall plastics recovery rate (mean true positive rate TPR ¡¥ ) of 99.76%, and a plastics purity (positive predictive value PPV ¡¥ ) of 99.88% were achieved. Additional simulations that were carried out based upon the experiments allow a prediction of the performance as a function of the signal-to-noise (S/N) ratio such that various system parameters can be adapted to the particular situation
%K Time-gated fluorescence spectroscopy
%K autofluorescence
%K fluorescent plastics labeling
%K hyperspectral imaging
%K plastics sorting and recycling
%K classification
%K image processing
%U https://journals.sagepub.com/doi/full/10.1177/0003702819831278